Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K39/395—Antibodies; Immunoglobulins; Immune serum, e.g. antilymphocytic serum
  • A61K39/44—Antibodies bound to carriers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
  • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
  • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
  • A61K47/56—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an organic macromolecular compound, e.g. an oligomeric, polymeric or dendrimeric molecule
  • A61K47/58—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an organic macromolecular compound, e.g. an oligomeric, polymeric or dendrimeric molecule obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. poly[meth]acrylate, polyacrylamide, polystyrene, polyvinylpyrrolidone, polyvinylalcohol or polystyrene sulfonic acid resin
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
  • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
  • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
  • A61K47/62—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being a protein, peptide or polyamino acid
  • A61K47/64—Drug-peptide, drug-protein or drug-polyamino acid conjugates, i.e. the modifying agent being a peptide, protein or polyamino acid which is covalently bonded or complexed to a therapeutically active agent
  • A61K47/645—Polycationic or polyanionic oligopeptides, polypeptides or polyamino acids, e.g. polylysine, polyarginine, polyglutamic acid or peptide TAT
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
  • C12N11/02—Enzymes or microbial cells immobilised on or in an organic carrier
  • C12N11/08—Enzymes or microbial cells immobilised on or in an organic carrier the carrier being a synthetic polymer
  • C12N11/089—Enzymes or microbial cells immobilised on or in an organic carrier the carrier being a synthetic polymer obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
  • C12N11/02—Enzymes or microbial cells immobilised on or in an organic carrier
  • C12N11/08—Enzymes or microbial cells immobilised on or in an organic carrier the carrier being a synthetic polymer
  • C12N11/089—Enzymes or microbial cells immobilised on or in an organic carrier the carrier being a synthetic polymer obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C12N11/096—Polyesters; Polyamides

Definitions

• This invention is in the fields of cell biology and cellular and molecular pharmacology.
• Macromolecules for example, such as proteins , nucleic acids , and polysaccharides , are not suited for diffusion or active transport through cell membranes simply because of their size.
• cell membranes form small vesicles which migrate from the periphery to the interior of the cell, a process known as pinocytosis. This form of transport is generally less efficient, however, than the diffusion or active transport of smaller molecules, and thus, the cellular uptake of macromolecules is limited.
• Ryser One method previously suggested by Ryser involves the use of cationic polymers, i.e., macromolecules which bear a sequence of positive charges. In this method, it was found that cellular uptake of some molecules could be improved by the simple presence in the experimental medium of such cationic polymers, especially homopolymers of positively charged amino acids such as poly-L-lysines, poly-D-lysines and poly-L-ornithines. See Ryser, H. J.-P., "Uptake of Protein by Mammalian Cells: An Underdeveloped Area", Science, 159, 390-6 (1968); and Ryser, H. J.-P., "Transport of Macromolecules, Especially Proteins Into Mammalian Cells", Proc. Fourth Internat.
• protoplasts prepared from mesophyll of Nicotiana tabacum can be infected by adding purified tobacco mosaic virus particles to a protoplast suspension in the presence of poly-L-ornithine whereas infection does not occur if poly-L-ornithine is not present. See Takebe, I. and Otsuki, Y., "Infection of Tobacco Mesophyll Protoplasts by
• Tobacco Mosaic Virus Proc. N.A.S., 64, pp 843-8 (1969).
• the cationic polymers form, at most, reversible complexes with the molecule to be transported and may interact at random with other molecules in the medium which means that the enhancement lacks specificity and reproducibility.
• Patent 4,013,511 describe a method for insolubilizing or immobilizing enzymes by covalently bonding the enzymes to anionic or cationic resins.
• polymeric resins are formed by reacting ethylenemaleic anhydride copolymer (EMA) and a suitable diamine, such as hydrazine, p,p'-diaminodiphenyl methane or a primary aliphatic diamine such as 2,6-diaminohexane.
• EMA ethylenemaleic anhydride copolymer
• suitable diamine such as hydrazine, p,p'-diaminodiphenyl methane or a primary aliphatic diamine such as 2,6-diaminohexane.
• Such resins are anionic, but can be made cationic by reacting them with N,N-dimethyl-1,3- propanediamine (DMPA) in the presence of an activating agent, such as dicylohexylcarbodiimide (DCC) .
• DMPA N,N-dimethyl-1,3- propanediamine
• DCC dicylohexylcarbodiimide
• Both the anionic and cationic polymeric resins can be covalently coupled to biologically active proteins such as enzymes.
• cationized ferritin can be formed by carbodiimide coupling of horse spleen ferritin to a diamine , namely , N,N-dimethyl-1,3-propanediamine. Cationized ferritin was proposed by these researchers as a tracer molecule for the detection of negatively charged groups on the surface of red blood cells. See Danon, D., Goldstein, L., Marikovsky, Y. and Skutelsky, E.,
• Hamster Kidney Cells J. Cell Biol., 66, 470 (1975). have molecular weights of 5000-500 , 000 and free carboxyl, amino or cycloimidocarbonate groups so that cytotoxic drugs containing amino or carboxyl groups can be covalently bonded thereto.
• This invention relates to a method for effecting or enhancing cellular uptake of molecules which are either excluded from or are taken up poorly by cells.
• the method is based upon the discovery that cellular uptake of such molecules can be increased if a conjugate of these molecules is formed by covalently bonding them to a cationic polymer.
• the cationic polymer appears to serve as a transport carrier for the excluded molecule, and the conjugated molecule is transported through cell membranes in a much more effective manner than the unconjugated molecule.
• a low density lipoprotein was cationized using the Danon et al. technique and shown to accumulate in human fibroblasts.
• macromolecules include proteins, such as enzymes, growth factors or other regulatory proteins, peptides, polypeptide hormones, lectins, antigens, antibodies or fragments thereof; informational macromolecules such as DNA and RNA; ⁇ ubcellular organelles and supermolecular particles such as chromosomes or components thereof; polysaccharides; etc.
• the method also has application to cellular uptake of excluded small molecules including nucleotides, nucleotide analogues, cofactors (e.g., cyanocobalamin), and drugs in general.
• drug is used in a broad sense to mean any substance used to treat a disease or to modify a condition in living organisms, particularly including human beings and other mammals.
• the degree of enhancement of cellular uptake has been found to be surprising and dramatic.
• the formation of a conjugate according to this invention has been found to increase cellular uptake by factors ranging up to several hundred-fold.
• this method has other significant advantages.
• this method may require the modification of only one carboxyl group located on the surface of a functional protein. Such minor modification is not likely to destroy biological function.
• a biologically active enzyme can be conjugated and transported into cells without losing its enzymatic activity.
• this method employs relatively small amounts of cationic polymer and is not limited to cationic polymers of large molecular size.
• the method is capable of providing dramatically increased cellular transport of molecules such. as drugs, co-factors, nucleotides, nucleotide analogues, etc.
• cationic polymers such as poly-L-lysine and poly-L-arginine, which are excellent substrates for physiologic proteolytic enzymes present in mammalian cells.
• these cationic polymers after having served as a transport carrier, can be digested or otherwise broken down inside the cells into normal physiologic by-products.
• FIG. 1 contains several plots of data obtained from consecutive elution fractions exiting from a chromatographic column loaded with a reaction mixture of horseradish peroxidase (HRP), poly-L-lysine (PLL) and carbodiimide reagent which plots represent the HRP content and HRP enzymatic activity of consecutive fractions as well as their ability to enter cells;
• FIG. 2 is a plot illustrating the uptake of labeled methotrexate (MTX) and labeled methotrexatepoly-L-lysine conjugate (MTX-PLL) by transportproficient and transport-deficient cells;
• FIG. 3 is a plot illustrating the growth inhibitory effects of methotrexate (MTX) and methotrexate poly-L-lysine conjugate (MTX-PLL) administered to cultures of transport-proficient and transportdeficient cells;
• FIG. 4 is a plot illustrating the inhibitory effect of free methotrexate (MTX), methotrexatepoly-L-lysine conjugate (MTX-PLL) and partially digested conjugate on dihydrofolate reductase activity, in vitro;
• FIG. 5 illustrates elution profiles of intracellular degradation products of 3H-MTX-PLL and 3 H- MTX-PDL conjugates
• FIGS. 6 and 7 are plots of data illustrating the effect of MTX and MTX-PLL conjugate on the survival of mice bearing an MTX-resistant and an MTX-sensitive lvmphosarcoma, respectively;
• FIG. 8 is a plot illustrating the growth of L 929 fibroblasts following their brief exposure to free 6-mercaptophosphoribosylpurine (6-MPRP), a mixture of free 6-MPRP and free poly-L-lysine (PLL), conjugated 6-MPRP-PLL, and trypsinized 6-MPRP-PLL conjugate;
• 6-MPRP free 6-mercaptophosphoribosylpurine
• PLL free poly-L-lysine
• PLL poly-L-lysine
• FIG. 9 is a plot illustrating the cellular uptake of labeled poly-L-lysine of varying molecular weight, corrected to equimolar concentrations
• FIG. 10 is a plot of data illustrating the level of mtracellular breakdown products of 125 I-PLL ingested by Sarcoma S-180 cell monolayers which are present in the cells and in the cell medium;
• FIG. 11 is a plot illustrating the in vitro effect of trypsin and heparin addition upon aggregates of human serum albumin (HSA) and poly-L-lysine (PLL) and aggregates of HSA and poly-D-lysine (PDL); and,
• FIG. 12 is a plot illustrating the in vitro effect of trypsin upon aggregates of HSA and each of poly-L-lysine (PLL), poly-L-ornithine (PLO) and poly-L-homoarginine(PLHA). Best Mode of Carrying Out The Invention There is a wide variety of molecules which can be covalently bonded to cationic polymers according to this invention to increase cellular uptake thereof.
• marcromolecules such as peptides, including oligopeptides, polypeptides and glycopeptides; proteins, including glycoproteins and lipoproteins; polysaccharid including mucopolysaccharides; lipids, including glycolipids; nucleic acids, including RNA and DNA, either in soluble form or as part of supramolecular structures or organelles.
• Many small molecules are also suitable, including drugs, cofactors (e.g., cyanocobalamin), nucleotide analogues, etc., which are either excluded or only poorly transported into cells.
• suitable conjugates can be formed for any molecule excluded from cells or only poorly transported into cells and which can be covalently bound to a cationic polymer. It is recognized, of course, that every molecule is probably transported into cells in some exceedingly small quantity and the term "excluded" is used herein in a functional sense rather than an absolute quantitative sense.
• biologically active enzymes can be covelently bonded to cationic polymers without losing their biological activity.
• intracellular content of biologically active enzymes can be increased by increasing thier membrane transport, as illustrated by Examples 6-10, below.
• Molecules which are excluded from cells are usually those normally excluded because of thier charge pattern, size, or for other physico-chemical reasons. This method also applies, however, to molecules which are not normally excluded but become excluded because of mutations.
• Such mutations may lead either to the loss of a transport mechanism e.g., certain forms of drug resistance, as illustrated by Examples 14, 15, 23, 25, 27 and 28 below, or to the loss or impairment of a receptor site on cells (e.g., certain forms of familialhypercholesterolemia) ot to the loss or impairment of a recognition marker on the molecules (e.g., certain mucopolysaccharidoses).
• a transport mechanism e.g., certain forms of drug resistance, as illustrated by Examples 14, 15, 23, 25, 27 and 28 below
• a receptor site on cells e.g., certain forms of familialhypercholesterolemia
• a recognition marker on the molecules e.g., certain mucopolysaccharidoses
• cationic polymer means a polymer or macromolecule containing positively charged groups sufficient to enhance cellular uptake of molecules covalently bound to it.
• Such polymers include homopolymers and copolymers (random and block); linear, branches and crosslinked polymers ; and synthetic and naturally occurring polymers.
• the positively charged groups are primary, secondary or tertiary amines which ionize at or around neutral pH.
• amine groups might be present as: amino groups in side chains as in poly (amino acids); amino groups included in a polymer backbone as in poly (amines); or amino substitutents added to an uncharged polymer, such as result in dextran substituted with diethylaminoethyl groups.
• the preferred cationic polymers are cationic poly(amino acids), such as poly-L-lysine, which can be represented by the structural formula
• n is an integer of 5 to 2000.
• a detailed description of poly (amino acids) is given in the following literature reference, the teachings of which are hereby incorporated by reference: Fasman, G. D., “Poly- ⁇ -amino Acids", Marcel Dekker, Inc., New York (1967).
• poly (amino acids) which are suitable include, but are not limited to, poly-L-lysine, poly-L-ornithine, poly-L-arginine, poly-L-homoarginine, poly-L-diaminobutyric acid, poly-L-histidine, the Doptical isomers thereof and copolymers thereof.
• Copolymers may include noncationic amino acid residues.
• Cationic poly (amino acids) are preferred because of the outstanding enhancement in cellular uptake which they provide.
• cationic polymers which are digested by proteolytic enzymes present in mammalian cells, and some poly (amino acids), such as, for example, poly-L-lysine and poly-L-arginine, provide this capability.
• poly (amino acids) such as, for example, poly-L-lysine and poly-L-arginine
• cationic polymers which are suitable in addition to poly (amino acids). These include polymers with neutral or anionic backones to which cationic groups have been bonded, as in the case of substituted polysaccharides (e.g., diethylaminoethyl dextran), substituted cellulose, substituted copolymers of ethylene and maleic anhydride, substituted lactic or glycolic acid polymers, etc.
• Polyamines such as for instance, poly (vinyl amine), or other cationic synthetic polymers, are also suitable. See Examples 9 and 10 below.
• Certain positively charged, naturally occurring macromolecules also serve as suitable cationic polymers.
• Specific examples include protamines and histones, such as. those found to increase cellular uptake of albumin by their simple presence. See Ryser, H. J.-P. and Hancock, R., Science, 150, pp 501-3 (1965).
• Other endogenous cationic macromolecules, especially peptides, endowed either with high rates of cellular transport or with special carrier properties might be isolated, purified and used as a carrier or vector for a molecule or macromolecule to be transported, as illustrated by Examples 11 and 12 below.
• multiple positive charges present on a polymer or macromolecule will enhance cellular uptake of that molecule. In most cases, such multiple positive charges will give the molecule a net positive charge. In other cases, however, the multiple charges may form an adequate sequence in the primary structure, or both, to cause enhanced cellular uptake, even though the molecule does not have an overall net positive charge.
• a molecule containing a limited number of positive charges at various intervals in its primary structure may fold in a manner such that a cluster of positive charges will be positioned in the same spatial area of its tertiary structure.
• a copolymer of poly (amino acid) with a neutral or negative net charge may contain a functionally important cluster of positive charges.
• cationic polymer refers not only to a macromolecule which has an overall positive net charge, but also includes macromolecules which contain sequential portions or spatial arrangements of positive charges sufficient to confer on them the transport properties of cationic polymers having a positive net charge thereon.
• Conjugation can be achieved by well-known chemical reactions. For example, carbodiimide coupling can be used to couple a carboxyl or phosphate group on the molecule to be conjugated with amino groups of a cationic polymer. Such reactions are described in the following articles, the teachings of which are hereby incorporated by reference: Halloran, M. J. and Parker, C.
• a typical conjugation reaction between a protein (P) and a poly (amino acid) (PAA) and employing a carbodiimide (CDI) catalyst can be illustrated as follows:
• Conjugation can also be achieved for certain molecules by glutaraldehyde coupling between amino groups on conjugate molecules with amino groups on cationic polymers.
• Glutaraldehyde coupling is described in the following literature references, the teaching of which are also incorporated by reference : Avrameas , S . and Ternynek, T., "Peroxidase Labelled Antibody and Fab Conjugates with Enhanced Intracellular Penetration" , Immunochemistry , 8 , 1175-1179 ( 1971) ; Gonatas , N. K.,
• reductive periodation can be useful to conjugate daunomycin or other carbohydrate-containing molecules to any amino group-containing carrier.
• reductive periodation can be useful to conjugate daunomycin or other carbohydrate-containing molecules to any amino group-containing carrier.
• Such a reaction is described in the following literature reference, the teaching of which are incorporated by reference: Hurwitz, E., Levy, R., Maron, R., Wilchek, M., Arnon, R., and Sela, M., Cancer Research, 35, 1175, (1975).
• Conjugation can also be achieved by using an intermediate molecule to link the drug to the carrier.
• intermediate molecules which might also be called spacer molecules
• spacer molecules examples are oligopeptides, succinyl anhydride, and maleic anhydride. Conjugations which incorporate such spacer molecules may require a two-step reaction, in which the spacer molecule is first linked to the drug and the spacer-drug conjugate is then linked to the carrier.
• covalently linked encompassed the use of such spacer molecules to bind the molecules to be transported to a cationic polymeric carrier.
• the rate of cellular uptake of conjugates prepared according to this invention can be varied by varying the molecular weight of the cationic polymer, such as poly L-lysine, employed to form the conjugate. Since it has been clearly demonstrated that the cellular uptake of labeled poly-L-lysine increase with its molecular weight (see Example 31 and FIG. 9), it can be expected that the same correlation will hold for other cationic polymers.
• the level of cellular uptake of the conjugated drug will be determined by the molecular weight of the poly-L-lysine carrier.
• the rate of cellular uptake of a conjugated drug can be predetermined by the molecular size of the homologous polymeric carrier.
• the rate of drug uptake also depends upon the number of drug molecules bound per unit weight of polymeric carrier.
• the rate and extent of intracellular release of molecules which are covalently bonded to cationic polymers to form conjugates can also be controlled. This can be done by choosing polycationic polymeric carriers which differ in their susceptibility to intracellular digestion. It is known, for instance, that poly-L-lysine is very susceptible to trypsin and other proteolytic enzymes, while poly-D-lysine is not. This is demonstrated by the data of Examples 17 and 19 below.
• methotrexate-poly-L-lysine (MTX-PLL) and methotrexate-poly-D-lysine (MTX-PDL) conjugate enter cells at comparable rates, as shown by Example 16, they have different biological effects: MTX-PLL strongly inhibit the growth of MTX-resistant cells; MTX-PDL has no such effect.
• Carriers with intermediate susceptibility to proteolysis can be devised by using copolymers of amino acids or homopolymers of unnatural amino acids.
• An example of the latter is given in Example 36 and FIG. 12, and these show that poly-L-homoarginine has a susceptibility to trypsin intermediate between that of poly-L-lysine and poly-L-ornithine.
• Another method of controlling the intracellular release of molecules which are covalently bonded to cationic polymers is to modify the bonding procedure.
• One important modification is the introduction of a spacer molecule which is bonded on one side to the drug and on the other side to the carrier, as described above. When such a spacer molecule is an oligopeptide, for example, and as such susceptible to proteolytic digestion, it can be selectively digested inside the cell and the drug can be released even when the cationic carrier is not itself digestible.
• Methotrexate is one example of a drug to which cells can be or can become resistant because of deficiencies in cellular uptake, but there are others.
• 5-fluorouracil, fluorodeoxyuridine, cytosine, arabinoside, vinblastin, vincristin, daunorubicin, doxorubicin, actinomycin, and bleomycin all suffer from similar limitations, and conjugations of these to cationic polymers would also increase cellular uptake of these respective drugs into otherwise drug-resistant cells.
• Another chemotherapeutic application of this invention arises in regard to those drugs to which cells become resistant due to inadequate intracellular activation of the drug.
• a prototype of a cancer drug to which tumor cells have become resistant for lack of drug activation is 6-mercaptopurine (6-MP), a purine analogue.
• 6-MP 6-mercaptopurine
• a common cause of tumor cell resistance to 6-MP is the loss of the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT) which activates 6-MP into its corresponding nucleotide.
• HGPRT hypoxanthine guanine phosphoribosyl transferase
• a nucleotide is the ribosyl- or deoxyribosyl phosphate of a purine or pyrimidine base
• a nucleotide analogue is the ribosyl- or deoxribosylphosphate of a purine or pyrimidine base analogue.
• 6-MP 6-mercaptophosphoribosyl purine
• a carbodiimide conjugation to covalently bond 6-MPRP to a poly (amino acid) through a terminal phosphate groups of the nucleotide analogue is given in Example 29 below and can be illustrated as follows:
• a similar conjugation could be made using the terminal phosphate of 6-mercaptophosphoriboxyl purine triphosphate (6-MPRPPP). Similar conjugations could, of course, be made to cationic polymers other than poly (amino acids).
• HGPRT also activates another with one or more different small molecules, or could itself be carrying a core of small molecules.
• LDL and ferritin are examples of macromolecules which have such special transport properties. Enhancement of cellular uptake of molecules normally excluded from cells or only poorly transported into cells can be utilized in many applications.
• cancer chemotherapy One area of application is the range of cancer treatments known generally as cancer chemotherapy, especially those involving drug-resistant cancers. Several important such chemotherapeutic applications are now described.
• Methotrexate a widely used cancer drug, is an analogue of folic acid and blocks an important step in .the synthesis of tetrahydrofolic acid which itself is a critical source of 1-carbon compounds utilized in the synthesis of thymidylate. Thymidylate is a building block that is specific, and therefore especially critical, for DNA synthesis.
• a conjugate formed between methotrexate and a cationic polymer, particularly a poly (amino acid) such as poly-L-lysine, would enhance cellular uptake of methotrexate and carry the drug into methotrexateresistant tumor cells.
• a carbodiimide coupling reaction for forming a suitable conjugate between methotrexate and a poly (amino. acid) can be illustrated as follows:
• PLL conjugate could be formed to overcome resistance to this drug due to lack of the enzyme HGPRT.
• pyrimidine analogues which undergo activation to nucleotide analogues. These include
• 5-fluorouracel 5-fluorouracil deoxyribose, 5-trifluoromethyl deoxyuridine , triacetyl-6-azauridine , cytosine arabinoside and adenosine arabinoside.
• the drug cytosine arabinoside for instance, is an analogue of cytosine riboside, which is a physiological nucleoside.
• a nucleoside is a ribosylated or deoxyribosylated purine or pyrimidine base.
• Cytosine arabinoside is a nucleoside in which the normal pentose, i.e., ribose, has been replaced by an abnormal pentose, i.e., arabinose.
• the activation of cytosine arabinoside to the corresponding nucleotide requires the attachment of a phosphate, whichis provided by adenosine triphosphate (ATP), the latter being converted to adenosine diphosphate (ADP).
• ATP adenosine triphosphate
• ADP adenosine diphosphate
• This reaction is catalyzed by the enzyme deoxycytidine kinase (DOCK), according to the reaction:
• cytosine arabinoside is without effect, since the lethal form of the drug, i.e., the cytosine arabinosylphosphate nucleotide, is not synthesized following cellular uptake of the drug.
• the activated form of this particular drug, and other similar drugs is commercially available but has heretofore been therapeutically inefficient because it is not transported into living cells.
• cationic polymers such as poly-L-lysine can be coupled to the terminal phosphate of the cytosine arabinosylphosphate nuceotide, or other nucelotide analogues to enhance their cellular uptake.
• Another form of drug resistance encountered in cancer chemotherapy is due to increased breakdown of a drug within the cell.
• One illustrative pathway of such inactivation is deamination of a pyrimidine base.
• cytosine arabinoside is more susceptible to deamination than its corresponding nucleotide.
• the direct introduction of a conjugate form of the nucelotide analogue cytosine arabinosyl phosphate would have the added advantage of being less susceptible to that form of inactivation and would thus be capable of overcoming a drug resistance that is due to increased drug destruction.
• this invention also has significant application in aspects of cancer chemotherapy not necessarily related to drug resistance.
• certain nucleotide analogues which were found to be biochemically very effective in cell free systems, have never been developed as potential drugs because of their poor transport into cells.
• One such nucleotide analogue which is a very powerful inhibitor of DNA synthesis in cell free systems is dideoxyadenosine triphosphate.
• this nucleotide analogue is incorporated into DNA, and once in corporated, blocks further elongation of the DNA molecule because of lack of the chemical group (3'-hydroxyl) required for polymerization.
• This compound cannot be used in the form of its precursor because cells are unable to synthesize a nucleotide of dideoxyadenosine.
• the nucleotide itself is not effective in therapy because it is not adequately taken up by cells.
• this nucleotide were covalently bonded to a cationic polymer, such as poly-L-lysine, it could be transported into cells and function therein to kill tumor cells.
• Still another application for this invention in cancer chemotherapy relates to a recently developed treatment for bone and muscle tumors wherein lethal doses of a drug, such as methotrexate, are administered, followed by administerion of large doses of folinic acid.
• a drug such as methotrexate
• This is known as rescue therapy because the doses of methotrexate administered would kill the patient by totally depleting the stores of folinic acid if the patient were not saved after a suitable interval by administration of large doses of folinic acid.
• Folinic acid is taken up readily by normal cells and less so by tumor cells, and thus the ratio of tumor to normal cells killed is improved. Such improvement could be especially significant in drug resistant tumors with deficiencies in methotrexate transport, becuase such deficiencies often extend to the transport of folinic acid.
• Comparable rescue procedures have not yet been worked out for drugs other than methotrexate, for instance, purine or pyrimidine analogues. In theory, they could be used in the course of therapy with 6-MP or any of the other purine or pyrimidine analogues mentioned previously, since the agents of rescue, i.e., normal nucleotides, are known and commercially available.
• the reason nucelotides have not been used for that purpose is, once again, that such nucleotides do not enter cells. If these nucelotides could be modified to penetrate into cells, they would immediately become available as rescue agents.
• the principle of this rescue treatment is to provide cells with the product of the enzymatic reaction that is blocked by the drug.
• this invention can also be used in antimicrobial chemotherapy.
• adenosine arabinoside a nucleoside very similar to cytosine arabinoside, has been found to be very effective in the treatment of Herpes Encephalitis, a viral infection of the brain.
• this drug must be activated in the cell to a full nucleotide, adenosine arabinosyl phosphate, which inhibits virus replication inside the cell.
• Crystalline human serum albumin (HSA), poly-L-lysine (PLL) of average molecular weight of 6700, and 1-ethyl-3-(3-dimethyl-aminopropyl)carbodiimide (EDC) were dissolved in equal amounts of 20 mg each in 0.8 ml water. This solution was incubated at 25° C for 3 hours with occasional shaking, and then loaded onto a Sephadex G100 chromatographic column which had been previously equilibrated with 0.01 M phosphate buffered saline (PBS), pH 7.0.
• PBS phosphate buffered saline
• Example 1 The procedures and reactants of Example 1 were used except that 20 mg of horseradish peroxidase (HRP) was substituted for HSA.
• HRP horseradish peroxidase
• the enzymatic activity of the pooled HRP-PLL fractions was compared to that of unconjugated HRP using an assay employing dianizidine as an electron acceptor. In this assay the rate of color development at 460nm ( ⁇ A 460nm /min) is used as an expression of enzymatic activity. It was found that the conjugation decreased the enzymatic activity of HRP by about 50 to 60 % . The enzymatic activity of each 2 ml fraction eluted from the column was determined using the same assay. The resulting data are shown as the dashed curve in FIG. 1.
• conjugate was prepared using the procedure and reactants of Example 1 except that prior to reaction, some of the crystalline HSA was radioiodinated with 125 I using the chloramm T-iodmation procedure. See Sonoda, S. and Schlamowitz, M., "Studies of 125 I Trace Labeling of Immunoglobin G by Chloramin-T,"
• Monolayers of L929 mouse fibroblast cells were grown to confluence in Eagle's MEM medium supplemented with non-essential amino acids and 10% fetal calf serum.
• Cell cultures containing unmodified labeled HSA and cell cultures containing labeled HSA-PLL were incubated for 60 mins. at 37° C in serum-free Eagle's MEM medium. After incubation, the monolayers of cells were washed twice with 5 ml of basal salt solution (BSS) at neutral pH and detached from the culture flask by brief exposure to trypsin.
• BSS basal salt solution
• the detached cells were washed twice by centrifugation and resuspension in 5 ml BSS, once by resuspension in 5 ml heparin-containing BSS (5 mg/ml) and twice more with 5 ml BSS.
• the purpose of the wash in heparin-BSS was to remove HSA-PLL conjugates adsorbed to the cell surfaces by complexing the polycation part of the conjugate with the polyanion heparin. After this extensive washing procedure, these cells were dissolved in IN sodium hydroxide.
• the protein concentration of this cell extract was determined by the method of Lowry as described by Lowry , O . H . , Rosebrough , N . S . , Farr, A. L., Randall, R. J., "Protein Measurement With the Folin Phenol Reagent" , J . Biol . Chem. , 193 , pp 265-75 (1951).
• 125 I radioactivity was measured in a gamma scintillation counter and expressed as ⁇ g of 125 I -HSA per mg of cell protein. This measurement was used as an expression of the cellular uptake of 125 I-HSA and of its PLL conjugate during the 60 min. incubation. The concentration of 125 I-HSA m either unmodified or conjugated form was 50 jug per ml of incubation medium throughout.
• the first experiment included a measurement of cellular uptake of labeled 125 I-HSA when administered to the cells in the presence of 10 ug/ml of PLL and the second experiment included a measurement of the cellular uptake of labeled 125 I-HSA when administered to the cells simultaneously with 50.ug/ml of non-labeled HSA-PLL conjugate.
• PLL serves as a carrier for the HSA protein covalently linked to it and significantly enhances transport of
• Example 3 REVERSAL OF ENHANCED CELLULAR UPTAKE OF HSA-PLL CONJUGATE BY TRYPSIN-TREATMENT The procedure of Example 3 was followed except that, prior to the experiments, part of the HSA-PLL conjugate was treated with trypsin. PLL is very sensitive to trypsin digestion, and enzymatic degradation of PLL in the conjugate would be expected to decrease the enhanced cellular uptake realized because of the PLL.
• the enzymatic reaction was stopped by diluting the 0.33 ml reaction mixture with 8.0 ml with Eagle's MEM medium containing 5% fetal calf serum (FCS). This dilution brought the HSA-PLL concentration to 54 ⁇ g/ml, which was roughly the same as in Example 3.
• Cellular uptake of the untreated HSA-PLL conjugate, of the trypsinized HSA-PLL conjugate, and of unconjugated HSA were measured following the procedure of Example 3. The results were: Uptake in 60 min. ( ⁇ g/mg cell protein)
• HSA-PLL conjugate decreased its uptake by approximately 50% when compared to the uptake of the non-trypsinized HSA-PLL conjugate. This indicates that the enhancement of uptake is determined by the PLL-content of the HSA-PLL conjugate, and further trypsinization would have been expected to further decrease enhancement.
• the data also indicate that the 5% fetal calf serum used to terminate trypsinization did not, by itself, modify the cellular uptake of the HSA-conjugate.
• the figures obtained for the cellular uptake of HSA-PLL and HSA are in close agreement with the data of Example 3.
• Example 3 The procedure of Example 3 was generally followed except that HRP and fractions of HRP-PLL obtained as described in Example 2 were employed instead of 125 I-HSA and 125 I-HSA-PLL, at a final concentration of 0.1 mg/ml.
• Monolayers of L929 fibroblasts were incubated for various periods of time in serum-free Eagle's medium containing HRP and HRP-PLL conjugate in concentrations ranging from 1.5 to 150 jug/ml.
• the incubation procedure was as described in Example 3, except that cells were grown to non-confluent monolayers on glass coverslips made to fit the tissue culture tubes.
• the washing procedure was modified as follows: after exposure to HRP, the monolayers were rinsed twice with basal salt solution (BSS).
• BSS basal salt solution
• coverslips bearing the monolayers After transferring the coverslips bearing the monolayers to clean tissue culture tubes, they were incubated for 5 minutes at 37° C in Heparin-BSS (5 mg/ml), rinsed 3 more times with BSS and fixed for 20 minutes at 25° C with 2.5% glutaraldehyde in 0.1M cacodylate buffer, pH 7.4. After 5 rinses with cacodylate buffer, the cells were stained for 10 minutes with 0.5 mg/ml diaminobenzidine solution in 0.05 M tris-buffer, pH 7.6, containing a final concentration of 0.01% H 2 O 2 .
• the monolayers were fixed for 60 min., at room temperature with 2% OsO 4 in 0.1 M cacodylate buffer. After 4 further rinses in cacodylate, the monolayers were dehydrated and mounted on glass slides.
• Electron microscopic pictures of cells exposed to HRP-PLL revealed horseradish peroxidase reaction product in the form of abundant dark, densely stained opacities localized within endocytotic vesicles, throughout the cytoplasm, including the paranuclear areas. In contrast, cells exposed to a 100-times greater concentration of conventional HRP, showed minimal amounts of stained reaction product. This finding proves that HRP-PLL conjugate are present within the cells following cellular uptake and confirms that the conjugation of HRP with PLL increases its cellular uptake by more than 200-fold.
• EXAMPLE 8 CELLULAR UPTAKE OF HRP-PLL CONJUGATE: REVERSAL OF ENHANCEMENT FOLLOWING TRYPSIN TREATMENT OF THE CONJUGATE This experiment was carried out as described in Example 7A except that, prior to the experiment, part of the HRP-PLL conjugate was treated with trypsin. PLL is very sensitive to tryptic digestion and it was expected that enzymatic degradation of the PLL moiety of the conjugate would decrease its cellular uptake. A 0.3 ml aliquot of HRP-PLL containing 0 . 85 mg/ml was incubated for 5 minutes in a 37° C water bath in presence of 30 pL of trypsin (0.25%).
• the enzymatic reaction was stopped by 1:500 dilution with serum free growth medium to reach a final concentration of 1.5 ⁇ q HRP/ml.
• the cellular uptake of the trypsinized HRP-PLL was compared with that of the corresponding nontrypsinized preparation used at the same concentration (1.5 ⁇ g/ml).
• Cells exposed to the trypsinized conjugate showed no sign whatever of intracellular HRP reaction product when observed under the light microscope.
• cells exposed to 1.5 ⁇ g/ml of HRP-PLL showed an amount of reaction product which was higher than that seen with amounts of 150 ⁇ g/ml unconjugated PLL.
• Example 4 This result is consistent with that of Example 4 and demonstrates that the enhanced uptake of the HRP-PLL conjugate is indeed caused by the PLL-moiety of the conjugate.
• the experiment also confirms the difference in uptake of HRP and HRP-PLL noted in Example 7A.
• Example 6 The procedure of Example 6 was generally followed except that the pooled fraction of HRP-PVA obtained as described in the preceding example was used in addition to the pooled HRP-PLL fraction obtained as described in Example 2.
• the cellular uptakes of HRP-PVA and HRP-PLL were measured in the same manner. Following exposure to HRP, or one of its two conjugates, the monolayers of L929 mojuse fibroblasts were washed and detached and the detached cells were washed as described in Example 3. The cells were then lysed and the cell extract used for measurement of enzymatic activity of HRP as described in Example 6.
• the cell-bound HRP activities following a 60-minute exposure to HRP, HRP-PVA and HRP-PLL were as follows: Cell-Associated Peroxidase Activity
• conjugation of HRP to PVA markedly increases the cellular uptake of enzymatically active HRP by L 929 cell monolayers. This increase is greater than that obtained with comparable amounts of HRP-PLL, especially at the lower concentration.
• conjugation of an enzyme to a cationic polymer other than a peptidic polymer can be at least as effective in enhancing the cellular uptake of active enzyme than conjugation to a cationic poly (amino acid).
• Tuftsin is a cationic tetrapeptide known to stimulate phagocytosis in leucocytes by interacting with a specific membrane receptor. See Najjar, V. A. and Nishoka, K., Nature, 228, 672-673 (1970); and Tzehoval, E. et al., Proc. Nat. Acad. Sci. U.S.A., 75, 3400-3404 (1978).
• the procedure and reactants of Example 1 were used except that tuftsin was substituted for PLL, and that the weights of reactants and the reaction volume were modified as follows: 6 mg 125 I-HSA. and 5 mg tuftsin were dissolved in 0 . 3 ml PBS to which 10 mg EDC was added.
• the concentration of 125 I-HSA in free and conjugated form was 50 ⁇ g/ml of incubation medium throughout. Cell-bound activity was measured after 1 and 60 minutes of incubation and the difference (60-1 min) was considered to represent net uptake. The results were:
• MTX methotrexate
• MTX conjugate a 0.1 ml aliquot of a MTX solution (20 mg/ml, pH 7) was added to a vial containing solid 3 H-MTX sodium salt (250 uCi, 18.5 Ci per m mol) The final solution was adjusted to pH 7 with 1 N HCl and was kept frozen as a stock 3 H-MTX
• MTX (CHO Pro -3 MTX 5-3) was obtained from Dr. W. F. Flintoff, University of Western Ontario, London, Ontario.
• a line of CHO wild-type cells from which the resistant cells had been derived (CHO WTT) was obtained from Dr. R. M. Baker, Massachusetts Institute of Technology, Cambridge, Ma.
• the 2 lines of CHO cells were grown as monolayers in Corning culture flasks with a flat surface of 25 cm 2
• the growth medium contained 10% fetal calf serum, penicillin (50 U/ml) and streptomycin (50 ⁇ g/ml). Cultures were started with 5 ⁇ 10 4 cells per flask.
• Non-confluent monolayers were washed once with serum-free growth medium and incubated at 37° C in 5 ml serum-free medium containing either 3 H-MTX or 3 H-MTX-PLL at a MTX concentration of 1 ⁇ 10 -6 M.
• the specific activities of both 3 H-MTX and 3 H-MTX-PLL were 72.5 mCi per m mole.
• the radioactive medium was removed at various times and the monolayers were washed twice with 5 ml Earle's balanced salt solution. Cells were then detached from the flask by brief exposure to trypsin. The cell suspension was centrifuged at low speed and the cell pellet was washed twice more with 5 ml balanced salt solution. The final pellet was dissolved in 1.0 ml 1 N NaOH and the protein content of each cell extract was determined by the method of Lowry. See Lowry,
• FIG. 2 shows the cellular uptake of free and conjugated methotrexate by the transport-proficient and transport-deficient cell lines as a function of time.
• the lower two curves represent the uptake of the free drug, and the upper two curves represent the uptake of the H 3 -MTX-PLL conjugates.
• the conjugated drug is taken up much more readily than the free drug by both cell types.
• the uptake of free H 3 -MTX by the transportdeficient cells is undetectable after 1 hour at the scale of Fig. 2, but is detectable in transportproficient cells.
• these measurements are in good agreement with those reported by Flintoff et al. See Flintoff, W. F., Davidson, S. V.
• the inhibitory effect of MTX on transport-proficient and transport-deficient cells is compared in the dose-response diagram of FIG. 3. Approximately 100-times higher concentrations of free MTX were needed to cause comparable inhibitions in the transportdeficient line as indicated by the horizontal distance between the corresponding curves. However, when transport-deficient cells were exposed to the MTX-PLL conjugate, their dose-response curve was shifted to the left (solid curve) and became indistinguishable from that of free MTX-acting on drug sensitive cells (broken curve). This suggests that the drug conjugate can overcome the transport deficiency inherent to the mutant line. Free and conjugated drug had approximately identical effects on the drug-sensitive line.
• OMPI sistance of both mutant lines to MTX was found to be of comparable magnitude and the resistance was overcome by MTX-PLL in comparable fashion .
• 3H-MTX-PDL was prepared as described in Example 13 from poly-D-lysine hydrobromide, MW 60,000.
• the cells were then washed extensively with BSS and were dissolved in IN NaOH,
• MTX transport proficient and deficient cell lines were treated with MTX or its conjugates as described in Example 15.
• concentration of the drugs was 1 ⁇ 10 -6 M of either free or conjugated MTX.
• MTX-PDL was prepared from poly-D-lysine hydrobromide with a molecular weight of 60,000 and was the same preparation as that used in Example 16.
• the growth inhibitory effects of MTX, MTX-PLL and MTX-PDL were as follows: Cell Line Number of Cells ⁇ 10 -6 After 4 Days in
• PRO -3 4.87 1.43 0.20 4.12 This shows that 1 ⁇ 10 -6 M of MTX-PDL has no significant effect on either cell line. At this conce tration, however, even free MTX can inhibit the growth of the resistant cells. Since there is no difference between the uptake of MTX-PLL and MTX-PDL by.
• Methotrexate-resistant cells PRO -3 MTX 5-3, were grown in a 75 cm flask and approximately one day before reaching confluence, were exposed for 24 hours at 37° C to 1 ⁇ 10 -6 M of 3 H-MTX-PLL and 3H-MTX-PDL. The labeled growth medium was then removed and the cell monolayers were washed twice with 15 ml buffered salt solution (BSS). The cells were detached from the flask by brief trypsinization and washed three times by low speed centrifugation in 5 ml BSS. The last cell pellet was dissolved in 1 ml of 1% sodium dodecysulfate (SDS) in 0.01 M phosphate buffer, pH 7.
• SDS sodium dodecysulfate
• a small amount (0.2-0.3 mg) of unlabeled MTX was added to each pellet before cell lysis as a carrier for traces of 3 H-MTX m the cell extract.
• the cell extract was then loaded onto a Sephadex G-25 column (1.5 ⁇ 24 cm) which had been equilibrated with SDS-phosphate-buf fer and the column was eluted with the same buffer.
• Each 2-ml fraction was collected from the effluent of the column and 0.5 ml aliquots from each fraction were mixed with 5 ml Aquasol and counted in a liquid scintillation counter.
• the unlabeled MTX added to the cell extract as carrier was identified by measuring the absorbance of each fraction at 257 nm.
• FIG. 5 shows typical elution profiles of the extracts of monolayers exposed to H-MTX-PLL (upper panel) and 3 H-MTX-PDL (lower panel).
• the arrows correspond to the total volume of the column.
• the solid curves show the radioactivity in each fraction, and the dotted curves indicate the unlabeled MTX added to the cell extract as carrier and internal marker.
• the cell extract from MTX-PLL treated cells shows a peak of radioactivity close to but not coincident with MTX. This peak, which represents about 25% of the total radioactivity in the cell extract, is believed to be a digestion product of MTX-PLL. No such peak is detected in the extract of cells exposed to MTX-PDL.
• Methotrexate (MTX) was conjugated with PLL of molecular weights of 3,100; 20,000; 70,000 and 130,000, using the procedure described in Example 13. These conjugates were purified by either Sephadex G-50 or
• Example 23 ANTITUMOR EFFECT OF MTX-PLL INJECTED INTRAVENOUSLY
• the P 1798 S/B tumor a cortisol-sensitive and methotrexate-resistant lymphosarcoma
• Cell suspensions were made by teasing minced pieces of tumor through a stainless steel screen, and 1 ⁇ 10 7 cells were injected subcutaneously in the left scapular region.
• mice were divided into 4 groups or 4 or 5 mice. One week or more after inoculation these groups were subjected to different treatments consisting of one daily injection of 0.2 ml of one of the following solutions: Group 1 (control), buffered saline; Group 2, PLL, (MW 2,700)
• mice Four groups of 8 BALB/c mice were inoculated subcutaneously with 1 ⁇ 10 7 cells of P 1798 S/B lymphosarcoma, a MTX-resistant, steroid-sensitive tumor. Treatment consisted of one daily 0.2 ml injection in the tail vein beginning on the sixth day after inoculation, and was continued until the death of the animal. The first two groups of mice served as controls and received 0.2 ml of either buffered saline (Group 1) or PLL
• mice were inoculated subcutaneously with 1 ⁇ 10 7 tumor cells and used 12 days after inoculation at a time when the tumor weight was about 5 g.
• the tumor bearing animals received, in the tail vein, one injection of 0.2 ml 3 H-MTX or 3 H-MTX-PLL containing a total of 3.2 and 2.0 ⁇ 10 6 CPM, respectively.
• the 3 H-MTX-PLL conjugate contained a PLL of 3,100 molecular weight.
• the amount of MTX injected as free MTX or MTX-PLL were 3.6 mg/kg and 3.2 mg/kg respectively.
• mice were sacrificed 24 hours after injection, their tumors were excised and a tissue slice including the center of the tumor was minced and teased through a stainless steel grid to yield a cell suspension.
• Triplicate aliquots containing 5 ⁇ 11 6 cells were processed for radioactive measurements in a liquid scintillation counter, and the average counts were corrected for the different in total radioactivity injected as free or conjugated drug.
• the results of two typical experiments were: CPM Per 5 x 10 6 Cells
• the disassociated cells were spun down to a loose pellet and resuspended in fresh medium to a cell concentration of 5 x 10 cells per 3.0 ml of medium.
• Comparable suspensions prepared from both tumors receive either 4 ⁇ 10 5 CPM of 3 H-MTX or 2.5 ⁇ 10 5 CPM of 3 H-MTX-PLL conjugate.
• the 3 H-MTX-PLL preparation was the same a that used in Example 25 (PLL MW 3,100).
• the molar concentrations of MTX in the incubation medium of the suspensions exposed to MTX and MTX-PLL were 8.8 ⁇ 10 -6 M and 7.3 ⁇ 10 -6 M respectively.
• a comparison of the data of Example 25 and 26 shows a difference in the relative uptake of free MTX by the cells derived from the MTX-sensitive and MTX-resistant tumor. This can be accounted for by the differences in concentration of MTX to which tumor cells were exposed in the in vivo and in vitro experiments.
• the average ratios of MTX-PLL/MTX taken up by cells of the resistant tumor are of the same order of magnitude (81 and 57) and are indeed very large in both examples.
• the data of these two examples are also consistent with the previous results obtained with two MTX-resistant and -sensitive lines of Chinese Hamster Ovary cells (see Example 14). They establish that the MTX resistance of the P1798 S/B tumor is indeed due to a deficiency in the membrane transport of MTX.
• a human lymphoblastoid tumor cell line proficient in MTX transport and a mutant line thereof, deficient in MTX transport and hence drug resistant, were provided by Dr. John S. Erikson, from the Medical College of Pennsylvania.
• the cells were grown in RPMl 1640 medium containing 10% fetal calf serum.
• 3 H-MTX-PLL 3 H-MTX-PLL, respectively.
• the 3 H-MTX-PLL preparation was the same as that used in Examples 25 and 26. Measurements were carried out in triplicate wells. The plates were incubated for 60 min. at 37°C in a 5% CO 2 atmosphere:. At the end of incubation, each well was harvested unto filter discs using a Sketron AS harvester. The discs were dried, placed in 2 ml Liquiflor and counted in a liquid scintillation counter. The cell-bound 3 H-MTX and 3 H-MTX-PLL radioactivity of the triplicates was averaged and corrected for the difference in -total radioactivity added as free or conjugated drug. The results were:
• the MTX-preparation was the same as that used in Examples 23 and 24 and had a PLL of 2,700 molecular weight.
• the multiwell plates were incubated for 24 hours at 37°C in a 5% CO 2 atmosphere after which the cells were washed twice with 2.0 ml of fresh medium. Triplicate aliquots (75 ul per well) of the washed suspensions were then reincubated in microwells of a Costar microplate, diluted to 0.2 ml with culture medium and 50 ⁇ Ci of 3 H-thymidine (25 ⁇ l) was added to each well. After an 18 hour incubation at 37°C, the cells were harvested onto filter discs, using a Sketron AS cell harvester.
• the data presented in this example indicate that the growth inhibitory effects recorded on Chinese hamster ovary cells (Examples 15, 17 and 20) and on the murine lymphosarcoma P1798 (Examples 23 and 24) are relevant to the treatment of human tumors.
• 6-MPRP (6-MPRP), was conjugated to PLL, MW 70,000, using the carbodiimide reagent, as described in Example 13 above.
• the reaction time was reduced to 1 hour at 25 °C.
• Column chromatography of the reaction product on Sephadex G-50 gave a sharp separation of conjugated and free 6-MPRP.
• the 2 forms of 6-MPRP had comparable UV absorption spectra, indicating that conjugation had not caused any modification of the mercaptopurine moiety.
• Cytocidal effects of 6-MPRP-PLL conjugate and of unconjugated 6-MPRP plus free PLL were compared using monolayer cultures of L-929 fibroblasts. Sparse monolayers in phase of exponential growth were exposed to 1 ⁇ 10 -5 M free or conjugated 6-MPRP for 1 h, 24h after inoculation. After exposure to the free or conjugated drug, the monolayers were kept growing for 2 days in standard growth medium, at which time no cytocidal effect could be detected. When the cells were subcultur and incubated for 7 additional days, the cells exposed to 6-MPRP-PLL failed to show any growth while cells exposed to a combination of f-ree 6-MPRP and free PLL grew at a rate undistinguishable from that of controls.
• 6-MPRP-PLL A preparation of 6-MPRP-PLL that had been briefly trypsinized caused a 50% inhibition of cell growth. Under other experimental conditions, i.e., when 6-MPRP and 6-MPRP-PLL were present for the duration of the experiment at a concentration of 2 x 10 M, both compounds had inhibiting effects.
• the data obtained are plotted in FIG. 8 and demonstrate: (1) that the 6-MPRP-PLL conjugate possesses biological activity; (2) that the conjugate can kill cells after a very short time of exposure in experimenta conditions under which the free nucleotide is ineffectiv and (3) that a nucleotide analog can be made to penetrat cells by employing PLL-conjugate.
• Poly-L-lysines of three different average molecular weights i.e., 38,000, 115,000 and 230,000, were radioiodinated using the Bolton-Hunter Reagent. See
• Confluent monolayers of Sarcoma S-180 were grown as described in Example 31. They were incubated for 60 minutes in serum free medium containing 0.2 ⁇ g/ml of
• 125 I-PLL of 115,000 molecular weight and high specific radioactivity.
• the labeled medium was removed and the monolayers were thoroughly washed with buffered salt solution (BSS)
• BSS buffered salt solution
• the monolayers were then reincubated in non-radioactive conditioned growth medium for various periods of time up to 24 hours.
• measurements were made of the acid soluble radioactivity both in the medium and in the cells.
• the acid soluble radioactivity of the medium was measured in the supernatant of medium treated at a final concentration of 20% trichloroacetic acid (TCA) .
• TCA trichloroacetic acid
• FIG. 10 represents the results of a typical experiments and shows the generation of TCA soluble labeled breakdown product of 125 I-PLL as a function of time.
• the upper curve corresponding to the acid soluble radioactivity of the culture medium, shows that labeled breakdown product of 125 l-PLL are released into the medium over the total period of reincubation and that this release increases linearly between 1 and 12 hours.
• the cell-associated acid soluble radioactivity remained essentially constant over a period of 24 hours.
• BHK baby hamster kidney cell line transformed by exposure to dimethylnitrosamine (DMN) , growing with a non-malignant phenotype at 32°C and a malignant phenotype at 38.5°C.
• DN ts dimethylnitrosamine
• the cells were grown as monolayers in Dulbecco's high glucose medium. The transition from normal to transformed phenotype requires 3 to 4 population doublings or approximately 56 hours of growth at 38.5°C.
• This experiment employed the cells described in the preceding example.
• the cells were grown, and exposed to radiolabeled PLL or PDL as described in Example 33 except that the labeled polymer concentration was approximately 0.3 pg/ml .
• the labeled medium was removed, and monolayers were thoroughly washed with buffered saline solution.
• An additional wash with saline containing 25 mg/ml dextran sulfate was carried out to remove surface-bound 125 I--polymers.
• the monolayers of cells with either phenotype were then reincubated for 24 hours at 32°C in the presence of unlabeled conditioned medium, after which the radioactivity of the medium and of the cells were measured separately.
• a second set of monolayers of either phenotype was reincubated for 24 hours at 38.5°C and processed in similar fashion.
• the total radioactivity measured in the medium and in the cells was expressed as ng 125 I-PLL per mg cell protein. The results were:
• Example 32 provide independent evidence that ingested PLL is readily hydrolyzed inside the cells to small molecular diffusible breakdown products, while ingested PDL is not. These observations are consistent with those of Examples 16, 17, 18 and 19 comparing the properties of MTX-PLL and MTX-PDL, and of Example 36 comparing the stability of HSA-PLL and HSA-PDL complexes.
• this Example shows that cells of the transformed phenotype tend to excrete a greater fraction of ingested PLL radioactivity into the medium than cells of a normal phenotype, suggesting a more efficient intracellular breakdown of PLL by cell of malignant phenotype. This difference is seen regardless of the temperature at which the experiment is carried out. This finding is of importance in view of the data we obtained with animal and human tumor cells
• Trypan Blue an anionic dye commonly used in histology, has the property of being excluded by intact healthy normal cells and is often used to test the integrity of living cultured cells. We observed that when PLL of 70,000 MW is added to an aqueous solution of Trypan Blue, it forms non-covalent soluble complexes which posses totally different staining properties than free Trypan Blue.
• HSA 0.5 mg/ml
• poly(amine acids) 10 pg/ml
• FIG. 11 shows that the rate of aggregate formation initiated by the mixture of HSA and poly (lysines) can be follows spectrophotometrically and that the rate is identical for both isomers.
• the addition of trypsin completely dissolved the aggregates of HSA-PLL, but had no effect on the aggregates of HSA-PDL.
• the latter aggregate could be dissociated to a large extent by the addition of 5 mg/ml heparin, a strong polyanion.
• Similar experiments were carried out with PLO and with PLHA except that the PLHA concentration was 30 pg/ml and trypsin was added after 30 minutes.
• the HSA-PLHA complexes showed intermediate susceptibility to trypsin, as shown in FIG. 12.
• This invention has industrial applicability in the clinical treatment of diseases, such as in the cancer and antimicrobial chemotherapeutic applications described herein.
• This invention can also be used in areas of drug therapy other than cancer and antimicrobial chemotherapy, whenever deficiency in cellular drug transport appears to be the cause of a poor response to drug treatment. Such areas may include metabolic, endocrine, cardiovascular and other diseases.
• Another area of application is the treatment of certain genetic diseases characterized by enzyme deficiencies.
• Several genetic diseases are characterized by the absence or abnormality of specific lysosomal enzymes.
• these enzymes have deficient catalytic functions and fail to hydrolyze natural substrates present in lysosomes (e.g., sphyngolipidosis or glycogenosis).
• lysosomes e.g., sphyngolipidosis or glycogenosis
• enzymes have a normal catalytic function when tested in cell free systems but lack recognition markers responsible for their celluiar uptake and for their normal distribution in diseased tissues. In both instances, it would be important to have available for possible therapy enzymes having an increased ability to enter into the diseased tissue.
• Any method to increase cellular uptake or decrease intracellular breakdown of such biological markers will increase their usefulness in cell biology and/or neurobiology, since their effectiveness is usually limited by the ratio of their cellular uptake to their intracellular digestion,
• This invention may also be useful in enhancing the cellular uptake of protein hormones or polypeptide hormones, such as insulin, especially when specific receptors for such hormones have been abolished or damaged by mutations or by diseases.
• protein hormones or polypeptide hormones such as insulin
• the method could also be used to increase the cellular uptake of pesticides, including insecticides, etc.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Bioinformatics & Cheminformatics (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Genetics & Genomics (AREA)
• Wood Science & Technology (AREA)
• Zoology (AREA)
• General Health & Medical Sciences (AREA)
• Microbiology (AREA)
• General Engineering & Computer Science (AREA)
• Biochemistry (AREA)
• Biotechnology (AREA)
• Biomedical Technology (AREA)
• Medicinal Chemistry (AREA)
• Pharmacology & Pharmacy (AREA)
• Epidemiology (AREA)
• Animal Behavior & Ethology (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Proteomics, Peptides & Aminoacids (AREA)
• Mycology (AREA)
• Immunology (AREA)
• Molecular Biology (AREA)
• Medicinal Preparation (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

Family

ID=27357136

Family Applications (1)

Country Status (4)

Cited By (20)

Families Citing this family (3)

Citations (4)

Family Cites Families (6)

• 1979
  • 1979-01-16 JP JP50039679A patent/JPS55500053A/ja active Pending
  • 1979-01-16 DE DE7979900200T patent/DE2967069D1/de not_active Expired
  • 1979-01-16 WO PCT/US1979/000029 patent/WO1979000515A1/en unknown
  • 1979-08-13 EP EP79900200A patent/EP0009498B1/en not_active Expired

Patent Citations (4)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events